<?php
declare(strict_types=1);
function  sum(int|float|string $x, int|float|string $y): int|float|false{
    if($x>=10||$y>=10)return  false;
    return $x+$y;
}
echo "3.6 + 4.8 =",sum(3.4,4.8),"\n";
echo "3.1 + 4.1 =", sum(3.1,4.1), "\n";
var_dump(sum(2,3));